Reactive transport modeling of enhanced rock weathering in soils for carbon removal
Abstract
A 1D reactive transport model was developed to simulate the application of ground rocks as agricultural soil amendments. This proposed technology, also known as "enhanced rock weathering", has promise for removal of atmospheric carbon. Predictive models for the in situ weathering rates of the applied rock materials are critical for assessing the feasibility and scalability of this technology. Our previous study has shown that weathering rates of the applied rocks are strongly influenced by site-specific conditions, e.g., soil hydraulic properties, which need to be considered in the design of operational parameters such as grain size and application depth. Here, we focus on the impacts of organic acids, including acetic acid and oxalic acid, on the weathering of rock materials and the resulting changes to soil chemistry. Our preliminary simulation results illustrate that the presence of organic acids can significantly promote rock weathering by forming aqueous complexes or precipitates with cations released by dissolution of rock amendments. The organic acids also impact the weathering reactions via pH and the complex soil reaction network. A more systematic evaluation is being carried out to examine the interactions between organic acids and applied rocks under a range of flow and transport conditions for different operational scenarios. Because organic acid concentrations in soils are mediated by microbial activity, understanding the effects of organic acids on silicate rock weathering will help design strategies that leverage microbial intervention for enhanced rock weathering.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H24J..07D